INSIDE

Published: August 15, 2006

Speaker of Iraqi Parliament Says He May Resign
The speaker of Iraq's Parliament said he was considering stepping down because of bitter enmity from Kurdish and Shiite political blocs, revealing the first major crack in Iraq's fragile unity government since it was formed nearly three months ago. ''Maybe now is the best time for me to withdraw,'' said Mahmoud al-Mashhadani, the third-ranking official in Iraq and a conservative Sunni Arab. PAGE A3

Threat Levels Lowered
Britain and the United States lowered threat assessment levels as the British police continued to hunt for clues in the reported plot to blow up American airliners. PAGE A13

Elusive Proof, Elusive Prover
Three years ago, a Russian mathematician announced he had solved a famous, intractable problem. Then he disappeared. Now mathematicians are calling the work a landmark. SCIENCE TIMES, PAGE F1

More Passenger Data Sought
Saying that the arrests last week in Britain point to a security gap in the current sharing of passenger data on international flights, American officials hope to close that gap with help from nations whose citizens do not need visas to travel to the United States. PAGE A13

Portrait of a Web Searcher
Internet companies like Yahoo and AOL are using computer models to analyze records of what their users search for and then displaying advertising meant to speak directly to individual interests and events. The practice, known as behavioral targeting, has stirred concerns about privacy. BUSINESS DAY, PAGE C1

New Art at Met (Opera, That Is)
Makiko Kudo's ''Princess Yue-yang'' is to be part of the first show at the Metropolitan Opera's contemporary art gallery, opening next month. Like all the works in the show, it was inspired by the heroine of an opera, here ''The First Emperor,'' by Tan Dun. THE ARTS, PAGE E1

Democrats See Security As Key Issue for Fall
After being outmaneuvered in the politics of national security in the last two elections, Democrats say they are determined not to cede the issue this year and are working to cast President Bush as having diminished the nation's safety.

Seeking to counter efforts to turn the apparent terrorist plot in Britain to Republican advantage, Democrats are using the arrests of the suspects to try to show Americans that the Iraq war has fueled Islamic radicalism and distracted Mr. Bush and the Republican Congress from shoring up domestic security. PAGE A15

Governors Oppose Guard Bill
In an unusual act of bipartisan unanimity, governors from all 50 states and Puerto Rico have joined to oppose legislation allowing the president to federalize National Guard troops during a disaster without the consent of local authorities. The governors say the legislation would undermine their autonomy. PAGE A14